Improvement in slide-valves



UNTED STATES PnsrnlwrA OFFICE.

CHARLES ROGERS, 0F ALLEGHENY, PENNSYLVANIA.

IMPROVEMENT IN SLIDE-VALVES.

Specitication forming part of Letters'Patent No. l 57,027, datedNovember 17, 1874; application filed September 19,1874.

To all whom it may concern:

Be it known that I, CHARLES ROGERS, of Allegheny, in the county ofAllegheny and State of Pennsylvania, have invented a new and valuableImprovement in Slide-Valves;

- and I do hereby declare that the following is a full, clear, and exactdescription of the construction and operation of the same, referencebeing had to the annexed drawings, making a part of this specification,and to the letters and gures of reference marked thereon.

This invention has relation to steam-engine valve-gear, as will behereinafter more fully described and claimed.

In the annexed drawings, A designates the cylinder for the main pistonB. G is the steam-chest, in which reciprocates a doubleheaded piston,C1, and a slide-valve, C2, which latter is movable with the piston C1. Ddesignates my auxiliary double-headed piston, which is representedarranged between the cylinder A and the steam-chest C; but any otherarrangement of this piston D may be adopted.` E designates the mainexhaustport, and a a the main steam-ports. There are also port-s b b,communicating with the steam-chest G, for actuating the piston andslide-valve therein, and ports o c for exhausting steam from the chestC, leaving the piston C1 free to act when steam is admitted at eitherend of the chest C. There are also, ports d d for admitting steam to-the chamber D', in which works the auxiliary piston D. El designatesthe port for conveying steam -to the steam-chest G.

The operation is as follows: The piston B in the drawing is at the endof theleft-hand stroke. for admitting steam at the left-hand end of thecylinder A through the port a, which would move the auxiliary piston Dto the position indicated in Fig. l. The port b on the let't is closed,and the corresponding port b on the right is open, so that during therighthand stroke of the piston B, when this piston passes the left-handport b, the steam has no communication with piston O1, as it is cut orfby one of the heads of piston D, but after The slide-valve G2 is in aposition.

down on one side of the auxiliary piston-A chamber D, and have nocommunication With it. The exhaust-port cuts into the chamber D', sothat the exhaust from ports o c may communicate with the main exhaust.

The ports b b are bored through the heads of the auxiliary piston D, orthey may be formed by grooving the heads'oi` this piston around theirperipheries. 1f the heads are bored through, as shown, there should be agroove and feather to prevent the piston from turning about its axis.

When steam is admitted through ports b b to move piston G1, it is freeto escape through ports o o, which ports b b are more than eight timesthe capacity of ports c c. The live steam can only escape at thesmallest ports while the slide-valve is making its stroke, which is veryrapid. It is necessary for piston D to remain fixed until after thesteam is let into one end of the main cylinder and exhausted at theother end, said steam acting on pistons D and B in the same manner andat the proper times. The cushioning of these pistons is regulated by thesize of the small ports o o and d d in not allowing the exhaust steam topass oft' too rapidly.

It will be observed that the double-headed piston D is cut away orrecessed, so as to leave small bearing-surfaces at its ends only. Thismethod of construction possesses the advantages of lightness andcomparatively small friction.

It will also be observed by my construction and arrangement of thesteam-ports, the cylinder C is relieved from any steam that may escapeby the pistons G1.

What I claim as new, and desire to secure by Letters Patent, is-

l. The exhaust-ports c c, connecting the steam-chest C with the chamberD surrounding the central portion of the double-headed piston D,recessed between its bearing portions, as shown, substantially asdescribed, and for the purpose set forth.

2. The double-headed piston G1, provided With the slide-Valve C2, ncombination With the auxiliary double-headed piston D, with ports b b,the main piston B, ports a a d d, exhaust-ports c o, all constructed,arranged,

and operated in the manner and for the purpose set forth.

In testimony that I claim the above I have hereunto subscribed my namein the presence of two Witnesses.

CHAS. ROGERS.

Witnesses:

ALONZO MOGUNE, IsAAo STEWART.

